LXR linux/tools/perf/util/sideband

   1// SPDX-License-Identifier: GPL-2.0-only
   2
   3#include "util/debug.h"
   4#include "util/evlist.h"
   5#include "util/evsel.h"
   6#include "util/mmap.h"
   7#include "util/perf_api_probe.h"
   8#include <perf/mmap.h>
   9#include <linux/perf_event.h>
  10#include <limits.h>
  11#include <pthread.h>
  12#include <sched.h>
  13#include <stdbool.h>
  14
  15int evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr,
  16                         evsel__sb_cb_t cb, void *data)
  17{
  18        struct evsel *evsel;
  19
  20        if (!attr->sample_id_all) {
  21                pr_warning("enabling sample_id_all for all side band events\n");
  22                attr->sample_id_all = 1;
  23        }
  24
  25        evsel = evsel__new_idx(attr, evlist->core.nr_entries);
  26        if (!evsel)
  27                return -1;
  28
  29        evsel->side_band.cb = cb;
  30        evsel->side_band.data = data;
  31        evlist__add(evlist, evsel);
  32        return 0;
  33}
  34
  35static void *perf_evlist__poll_thread(void *arg)
  36{
  37        struct evlist *evlist = arg;
  38        bool draining = false;
  39        int i, done = 0;
  40        /*
  41         * In order to read symbols from other namespaces perf to needs to call
  42         * setns(2).  This isn't permitted if the struct_fs has multiple users.
  43         * unshare(2) the fs so that we may continue to setns into namespaces
  44         * that we're observing when, for instance, reading the build-ids at
  45         * the end of a 'perf record' session.
  46         */
  47        unshare(CLONE_FS);
  48
  49        while (!done) {
  50                bool got_data = false;
  51
  52                if (evlist->thread.done)
  53                        draining = true;
  54
  55                if (!draining)
  56                        evlist__poll(evlist, 1000);
  57
  58                for (i = 0; i < evlist->core.nr_mmaps; i++) {
  59                        struct mmap *map = &evlist->mmap[i];
  60                        union perf_event *event;
  61
  62                        if (perf_mmap__read_init(&map->core))
  63                                continue;
  64                        while ((event = perf_mmap__read_event(&map->core)) != NULL) {
  65                                struct evsel *evsel = evlist__event2evsel(evlist, event);
  66
  67                                if (evsel && evsel->side_band.cb)
  68                                        evsel->side_band.cb(event, evsel->side_band.data);
  69                                else
  70                                        pr_warning("cannot locate proper evsel for the side band event\n");
  71
  72                                perf_mmap__consume(&map->core);
  73                                got_data = true;
  74                        }
  75                        perf_mmap__read_done(&map->core);
  76                }
  77
  78                if (draining && !got_data)
  79                        break;
  80        }
  81        return NULL;
  82}
  83
  84void evlist__set_cb(struct evlist *evlist, evsel__sb_cb_t cb, void *data)
  85{
  86        struct evsel *evsel;
  87
  88        evlist__for_each_entry(evlist, evsel) {
  89                evsel->core.attr.sample_id_all    = 1;
  90                evsel->core.attr.watermark        = 1;
  91                evsel->core.attr.wakeup_watermark = 1;
  92                evsel->side_band.cb   = cb;
  93                evsel->side_band.data = data;
  94      }
  95}
  96
  97int evlist__start_sb_thread(struct evlist *evlist, struct target *target)
  98{
  99        struct evsel *counter;
 100
 101        if (!evlist)
 102                return 0;
 103
 104        if (evlist__create_maps(evlist, target))
 105                goto out_delete_evlist;
 106
 107        if (evlist->core.nr_entries > 1) {
 108                bool can_sample_identifier = perf_can_sample_identifier();
 109
 110                evlist__for_each_entry(evlist, counter)
 111                        evsel__set_sample_id(counter, can_sample_identifier);
 112
 113                evlist__set_id_pos(evlist);
 114        }
 115
 116        evlist__for_each_entry(evlist, counter) {
 117                if (evsel__open(counter, evlist->core.cpus, evlist->core.threads) < 0)
 118                        goto out_delete_evlist;
 119        }
 120
 121        if (evlist__mmap(evlist, UINT_MAX))
 122                goto out_delete_evlist;
 123
 124        evlist__for_each_entry(evlist, counter) {
 125                if (evsel__enable(counter))
 126                        goto out_delete_evlist;
 127        }
 128
 129        evlist->thread.done = 0;
 130        if (pthread_create(&evlist->thread.th, NULL, perf_evlist__poll_thread, evlist))
 131                goto out_delete_evlist;
 132
 133        return 0;
 134
 135out_delete_evlist:
 136        evlist__delete(evlist);
 137        evlist = NULL;
 138        return -1;
 139}
 140
 141void evlist__stop_sb_thread(struct evlist *evlist)
 142{
 143        if (!evlist)
 144                return;
 145        evlist->thread.done = 1;
 146        pthread_join(evlist->thread.th, NULL);
 147        evlist__delete(evlist);
 148}
 149